Spiral element and method for making same

ABSTRACT

A spiral element formed by a method which may comprise the steps of providing a generally arcuate blank of arcuate length not greater than about 180*, applying force to the ends of the blank to laterally twist such ends simultaneously in opposite directions, and during said twisting restraining the arcuate center of the blank from lateral twisting and maintaining the arcuate lengths of the blank between its arcuate center and its ends unsupported whereby the twisting forms the blank to spiral configuration.

United States Patent Moodey [451 June6, 1972 [54] SPIRAL ELEMENT AND METHOD FOR MAKING SAME 211 App]. No.: 54,747

340,024 4/1886 Williams ..72/4l4 843,659 2/1907 Baumann ..72/371 Primary Examiner-Lowell A. Larson Attorney-Carl R. Horten, David W. Tibbott and Robert R. Paquin [57] ABSTRACT A spiral element formed by a method which may comprise the steps of providing a generally arcuate blank of arcuate length 3 is not greater than about 180, applying force to the ends of the [58] 380 386 4'2 blank to laterally twist such ends simultaneously in opposite f directions, and durin said twisting restrainin the arcuate center of the blank from lateral twisting and maintaining the l 56] References Cited arcuate lengths of the blank between its arcuate center and its ends unsupported whereby the twisting forms the blank to UNITED STATES PATENTS Spiral configuration 75,182 3/1868 Mix ..72/371 9 Claims, 5 Drawing Figures f l I 1 I 220 LL30 240 I2 1 260 '2 28 L I t I SPIRAL ELEMENT AND METHOD FOR MAKING SAME The present invention relates to the manufacture of spiral elements and more particularly to the provision of a new and improved method for the manufacture of a spiral element and the element produced by this method.

Conventionally, spirals have been employed for many purposes including, by way of example, mounting of the cutting bits on the rotary cutting heads or drums of continuous mining machines. Conventional methods for the manufacture of such a spiral, however, generally either inherently greatly limit the maximum possible cross-section or thickness of the spiral, undesirably inherently weaken the spiral during its manufacture, result in a spiral possessing no substantial geometric accuracy and/or are believed to be undesirable or unsuitable for other reasons. The failure of such conventional methods to provide a satisfactory spiral is believed to be most pronounced in those instances in which the spiral is to be employed on a rotary cutting head of a continuous mining machine and in those other instances in which the strength of the spiral is of great importance.

An object of the present invention is to provide a new and improved method for the manufacture of a spiral element, which method is particularly adapted to produce a stronger spiral element than normally results from prior conventional methods for its purpose.

Another object of the invention is to provide a new and improved method for the manufacture of a spiral element, which method is particularly adapted to avoid substantial weakening of the element during its manufacture.

Another object is to provide a new and improved method for the manufacture of a spiral element, which is capable of producing a spiral element of greater cross-section or thickness than normally possible with prior conventional methods.

Another object is to provide a new and improved spiral element made through the employment of the method of the invention.

These objects, and those other objects and advantages of the invention which will be apparent from the following description taken in connection with the accompanying drawings, are attained by the provision of a method which, generally considered, comprises the steps of providing a blank of generally arcuate configuration and twisting such blank by force applied at locations spaced by a therebetween arcuate length of the blank whereby the blank is thereby formed to spiral configuration.

Referring to the drawings:

FIG. 1 is a top or plan view of a blank employed in the practice of the method of the invention.

FIG. 2 is an elevational view of the blank in a press preparatory to its twisting to spiral configuration;

FIG. 3 is an elevational view of a spiral element produced by the practice of the method of the invention;

FIG. 4 is an elevational view of a rotary cutting head or drum of a continuous mining machine provided with a plurality of spiral elements constructed through the practice of the method of the invention and arranged spirally end-to-end; and

FIG. 5 is an enlarge fragmentary view of the rotary cutting head shown in FIG. 4 illustrating one of the spiral elements thereon.

Referring more particularly to the drawings wherein similar reference characters designate corresponding parts throughout the several views, in the practice of the method of the invention there is initially provided a generally arcuate blank which may be formed in any suitable conventional manner from heavy gauge steel or any other desired material capable of being twisted to spiral configuration and thereafter permanently retaining such configuration. The blank 10, as illustrated in FIG. 1, is of 180 arcuate length and includes ends 12 spaced from the arcuate center 14 of the blank 10 by arcuate lengths 16 of the latter. The blank 10 has flat or planar side faces 10a and may be of any cross-section or thickness capable of being twisted under pressure; for example, in the instance of a heavy gauge steel blank 10 it has been found that a thickness of in excess of 1 inch is satisfactory. The inner radius of the blank 10 is predetermined in accordance with the desired inner radius of the produced spiral element and in those instances in which the spiral element is to be mounted circumferentially around a cylinder, for example a rotary cylindrical head of a continuous mining machine, is preferably selected slightly larger than the outer radius of the cylinder to ensure that the produced spiral element is the best fit thereon. Moreover, although the illustrated blank 10 is of arcuate length, it will be understood that this length has been shown as a preferred length and alternatively the employed blank may be of other desired arcuate length. It is believed, however, that the maximum arcuate length of the blank 10 should not exceed about 180 for the most satisfactory results to be attained.

In accordance with the present invention, the provided blank 10 is twisted to spiral configuration by force applied to the blank 10 at locations spaced by a therebetween arcuate length of the blank 10. More particularly, as illustrated in FIG. 2, the blank 10 may be positioned between the platens 18, 20 of a conventional high pressure press provided with an open die having cooperative die elements 22, 26, and 24, 28 respectively. The illustrated die elements 22, 24 are mounted on the platen 18 at locations predetermined such that the elements 22, 24 are caused to simultaneously engage the blank upper side face 10a at the opposite ends 12 of the blank 10; and the die elements 26, 28 are mounted on the platen 20 opposite the elements 22, 24 respectively, such that the elements 26, 28 simultaneously similarly engage the blank lower side face 10a. The die elements 22, 24, 26, 28 are all of identical size and shape and, as viewed in FIG. 2, have parallel angled blank en gaging surfaces 22a, 24a, 26a, 28a all sloping downwardly to the left. Thus, during the closing of the platens 18, 20 with a blank 10 therebetween, the twisting force applied to one end 12 of the blank 10 by the complementary die elements 22, 26 laterally twists such end 12 downwardly towards its outer circumference while simultaneously the twisting force applied to the other blank end 12 by the cooperating elements 24, 28 oppositely twists the latter blank end 12 downwardly towards its inner circumference.

In addition, as shown in FIG. 2, the platens 18, 20 also carry opposed cooperating holding or restraining elements 30, 32 respectively, which have planar nonnal blank engaging surfaces 30a, 32a to engage opposite side faces 10a at the arcuate center 14 of the blank 10 when the latter is positioned between the platens 18, 20 with its ends intermediate the cooperating pairs of die elements 22, 26 and 24, 28. The restraining elements 30, 32 are constructed of sufficient height that their engaging surfaces 30a, 320 so engage the blank side faces 10a during the closing of the platens 18, 20 (and resultant opposite twisting of the blank ends 12) to thereby restrain the center 14 of the blank 10 from any substantial lateral twisting. The engaging surfaces 30a, 32a, and also the engaging surfaces 22a, 24a, 26a, 28a, as illustrated are of greater width than the blank 10.

In the practice of the method of the invention, as illustrated in FIG. 2, the blank 10 is located between the platens 18, 20 with its ends 12 intermediate the cooperating pairs of die elements 22, 26 and 24, 28 and its arcuate center 14 intermediate the restraining elements 30, 32. The arcuate lengths of the blank 10 between the center 14 and ends 12 are, as illustrated in FIG. 2, unsupported. Then, the platens 18, 20 are closed on the blank 10 whereupon the pairs of die elements 22, 26 and 24, 28 simultaneously exert twisting forces on the blank ends 12 to twist such ends 12in opposite lateral directions. During the closing of the platens 18, 20 and resultant twisting of the blank 10, the surfaces 30a, 32a of the restraining elements 30, 32 engage the center 14 of the blank 10 to, as aforementioned, restrain such center 14 from any substantial lateral twisting. Thus, the blank 10 is thereby formed to a spiral form or configuration such as shown in FIG. 3 to produce a spiral element 36 which may, as illustrated in FIGS. 4 and 5, be welded or mediate these locations can, of course, deviate from the corresponding portion of a true or perfect geometric spiral only in an extremely small manner. As a result, the spiral element provided by the hereinbefore described method is substantially more geometrically accurate than the spirals produced by 'prior conventional methods; and the practice of such beforedescribed method results in the provision of a spiral element substantially improved over those produced by conventional methods for its purpose. Also, as the geometry of the produced spiral element is readily and simply adjustable by mere variation in theelements employed on the platens 18,

20, this geometry may be easily varied substantially as desired. Moreover, it will be seen that the previously described method is capable of producing a spiral element of any cross-section of thickness capable of being formed by twisting of the blank, and also that said method does not necessitate the formation of any cuts or slots in the spiral element such as might weaken it during its manufacture.

' in summary, the hereinbefore described method provides a spiral element through the steps comprising providing a generally arcuate blank of arcuate length at least preferably not greater than about 180, applying twisting force to the ends of such blank to laterally twist such ends simultaneously in opposite directions, and during said twisting restraining the arcuate center of the blank from lateral twisting and maintaining the arcuate lengths of the blank between its longitudinal center and its ends unsupported whereby the twisting forms the blank to spiral configuration.

It will be understood, however, that the hereinbefore described embodiment of the invention has been given by way of illustration and that the invention is not limited merely to this single described embodiment, but rather contemplates other embodiments and variations in accordance with its teachings. For example, and not by way of limitation, it is possible to produce a spiral from the blank by merely twisting the blank in the aforedescribed manner without holding the blank intermediate of the application of the twisting forces. It is believed, however, that this modified method may not produce as geometrically true a spiral as the embodiment of the method first hereindescribed as this last described or modified method only ensures that the produced spiral is geometrically correct at the two locations at which the twisting forces are applied. Similarly, many other embodiments or modifications of the method will become apparent to those skilled in the art from the hereinbefore disclosure.

Having thus described my invention, 1 claim:

1. In a method of forming a spiral element, the steps comprising providing a blank of generally arcuate configuration, and applying external twisting force only to the ends of the blank to laterally twist such ends in opposite directions and thereby form the blank to spiral configuration. c

2. The'method according to claim 1 wherein the twisting force is simultaneously applied to the ends of the blank.

3. The method according to claim 1, wherein the provided blank is of arcuate length not greater than about 4. The method according to claim 1, wherein the provided blank includes opposite planar side faces.

5. In a method of forming a spiral element, the steps comprising providing a blank of generally arcuate configuration, and applying twisting force to the blank at locations spaced by a therebetween arcuate length thereof to thereby twistthe blank to spiral configuration, while during the application of the twisting force restraining from twisting a portion of said arcuate length spaced arcuately of the blank from said locations. 6. The method according to claim 5, wherein the restrained portion of the blank is at the center of said arcuate length thereof.

7. A method of forming a spiral element, comprising the steps of providing a blank of generally arcuate configuration, and applying twisting force to the blank at locations spaced by a therebetween arcuate length thereof to thereby twist the blank to spiral configurations, and wherein the twisting force is applied by a press having dies provided with cooperative angled surfaces for simultaneously oppositely laterally twisting the blank at said locations.

8. In a method of forming a spiral element, the steps comprising providing a generally arcuate blank of arcuate length not greater than about 180, applying twisting force to the ends of the blank to laterally twist such ends simultaneously in opposite directions, and during said application of twisting force restraining the arcuate center of the blank from lateral twisting and maintaining the arcuate lengths of the blank between its arcuate center and its ends unsupported whereby the twisting forms the blank to spiral configuration.

9. The method according to claim 8, wherein the blank is twisted by a press provided with dies having portions cooperative to restrain the arcuate center of the blank from lateral twisting and also having angled portions cooperating for simultaneously laterally twisting the ends of the blank. 

1. In a method of forming a spiral element, the steps comprising providing a blank of generally arcuate configuration, and applying external twisting force only to the ends of the blank to laterally twist such ends in opposite directions and thereby form the blank to spiral configuration.
 2. The method according to claim 1, wherein the twisting force is simultaneously applied to the ends of the blank.
 3. The method according to claim 1, wherein the provided blank is of arcuate length not greater than about 180*.
 4. The method according to claim 1, wherein the provided blank includes opposite planar side faces.
 5. In a method of forming a spiral element, the steps comprising providing a blank of generally arcuate configuration, and applying twisting force to the blank at locations spaced by a therebetween arcuate length thereof to thereby twist the blank to spiral configuration, while during the application of the twisting force restraining from twisting a portion of said arcuate length spaced arcuately of the blank from said locations.
 6. The method according to claim 5, wherein the restrained portion of the blank is at the center of said arcuate length thereof.
 7. A method of forming a spiral element, comprising the steps of providing a blank of generally arcuate configuration, and applying twisting force to the blank at locations spaced by a therebetween arcuate length thereof to thereby twist the blank to spiral configurations, and wherein the twisting force is applied by a press having dies provided with cooperative angled surfaces for simultaneously oppositely laterally twisting the blank at said locations.
 8. In a method of forming a spiral element, the steps comprising providing a generally arcuate blank of arcuate length not greater than about 180*, applying twisting force to the ends of the blank to laterally twist such ends simultaneously in opposite directions, and during said application of twisting force restraining the arcuate center of the blank from lateral twisting and maintaining the arcuate lengths of the blank between its arcuate center and its ends unsupported whereby the twisting forms the blank to spiral configuration.
 9. The method according to claim 8, wherein the blank is twisted by a press provided with dies having portions cooperative to restrain the arcuate center of the blank from lateral twisting and also having angled portions cooperating for simultaneously laterally twisting the ends of the blank. 